How many BTU for a bedroom?
Too few BTU and the room won’t cool; too many and you overpay.
The quick rule
Budget roughly 340 BTU per m². A 12 m² bedroom needs ~9,000 BTU; 20 m², ~12,000 BTU. Add ~10% for very sunny rooms or top-floor spaces under the roof.
Don’t oversize too much
An oversized unit cools fast then shuts off without dehumidifying well. Stay close to the room’s real need.